Clinical evidence suggests that progesterone may reduce the presence of adenosis in the genital tracts of diethylstilbestrol (DES)-exposed human females. Testing of the efficacy of progesterone therapy for the DES exposed human female is proposed in this study using the neonatally estrogen treated mouse as the model system. Neonatal female BALB/c mice will receive subcutaneous injections of 1 or 25 ug of estradiol (E2) for five days beginning 24 hours following birth. The mice will be weaned at 25 days and randomly distributed among the following experimental groups: A) animals receiving no further treatment, B) those receiving a high dose of Provera (R, C) those receiving a high dose of Provera (R) and ethinyl-estradiol-17, and D) those receiving ethinyl-estradiol 17B only. All groups will receive normonal treatment via silastic implants. Treatment will begin at two months of age and will continue for one year. Mice from each group will be selected at three month intervals and subjected to vaginal smears for ten consecutive days followed by sacrifice. One half of the cervicovaginal (CV) tract will be frozen and then analyzed for the presence of cytoplasmic and nuclear P receptor (PR) and E (ER) receptor. The other half of the CV tract will also be frozen and sectioned for histologic examination.